US4649807A - Method for preventing dust depositions or build-ups in off-gas channels of electrothermal smelting furnaces - Google Patents

Method for preventing dust depositions or build-ups in off-gas channels of electrothermal smelting furnaces Download PDF

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Publication number
US4649807A
US4649807A US06/710,147 US71014785A US4649807A US 4649807 A US4649807 A US 4649807A US 71014785 A US71014785 A US 71014785A US 4649807 A US4649807 A US 4649807A
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Prior art keywords
gas
furnace
dust
build
channels
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US06/710,147
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Torbjorn Aasen
Bjarne Thogersen
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Elkem ASA
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Elkem ASA
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Assigned to ELKEM A/S, A CORP. OF THE KINGDOM OF NORWAY reassignment ELKEM A/S, A CORP. OF THE KINGDOM OF NORWAY ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: AASEN, TORBJORN, THOGERSEN, BJARNE
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D25/00—Devices or methods for removing incrustations, e.g. slag, metal deposits, dust; Devices or methods for preventing the adherence of slag
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D17/00—Arrangements for using waste heat; Arrangements for using, or disposing of, waste gases
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D17/00—Arrangements for using waste heat; Arrangements for using, or disposing of, waste gases
    • F27D17/001—Extraction of waste gases, collection of fumes and hoods used therefor
    • F27D17/002—Details of the installations, e.g. fume conduits or seals

Definitions

  • the present invention relates to a method for preventing depositions or build-ups of dust in off-gas channels for electrothermal smelting furnaces.
  • the furnace off-gas has a high concentration of dust.
  • Ferrosilicon has usually been produced in so-called open furnaces where air from the suroundings of the furnace is sucked into the open space between the smoke hood and the top of the furnace pot.
  • the volume of air which in this way enters into the furnace is several hundred times greater than the gas which evolved from the furnace itself. This gives a complete and very fast combustion of combustible gases in the furnaces off-gas and also a very rapid cooling of the furnace off-gas.
  • concentration of dust in the gas which enters into the furnace off-gas channels is reduced due to the increased gas volume.
  • cooled, recirculated furnace off-gas or air are used as additional gas.
  • cooled and unburned off-gas is used as additional gas.
  • air is used as additional gas.
  • the temperature of the additional gas which is blown into the off-gas channels is preferably kept below the sintering temperature of the dust in the dust-containing furnace off-gas.
  • FIG. 3 is a vertical view of a part of a furnace roof and a furnace off-gas channel showing the cooling means.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Environmental & Geological Engineering (AREA)
  • Waste-Gas Treatment And Other Accessory Devices For Furnaces (AREA)
  • Resistance Heating (AREA)
  • Cable Accessories (AREA)
  • Control Of Combustion (AREA)

Abstract

A method for preventing deposits or build-ups of dust in off-gas channels for dust-containing off-gases from electrothermal smelting furnaces. This is done by blowing an additional gas tangentially into the furnace off-gas channels at the positions where build-ups or deposits of dust normally occurs. Hence a gas spiral is provided between the inner wall of the furnace off-gas channels and the dust-containing, hot furnace off-gas. Recirculated and cooled furnace off-gas is preferably used as additional gas. For open furnaces where the furnace off-gas is completely combusted before it enters into the furnace off-gas channels, air can be used as additional gas. The temperature of the additional gas is preferably kept below the sintering temperature of the dust in the furnace off-gas.

Description

The present invention relates to a method for preventing depositions or build-ups of dust in off-gas channels for electrothermal smelting furnaces.
In production of ferro alloys such as for example ferrosilicon in electrothermal smelting furnaces, the furnace off-gas has a high concentration of dust. Ferrosilicon has usually been produced in so-called open furnaces where air from the suroundings of the furnace is sucked into the open space between the smoke hood and the top of the furnace pot. The volume of air which in this way enters into the furnace is several hundred times greater than the gas which evolved from the furnace itself. This gives a complete and very fast combustion of combustible gases in the furnaces off-gas and also a very rapid cooling of the furnace off-gas. In addition the concentration of dust in the gas which enters into the furnace off-gas channels is reduced due to the increased gas volume.
For environmental reasons and also in order to reduce the total volume of off-gas, electrothermal smelting furnaces have in recent years been more and more closed and for some processes the furnaces are now completely closed.
As the furnaces now are more or less closed and thus a smaller amount of surrounding air is sucked into the furnaces, the concentration of dust in the off-gases has increased. This has lead to problems with depositions or build-ups of dust in the transition between the furnace roof or smoke hood and the off-gas channels. It has been tried to design the off-gas channels as streamlined as possible in order to get an even gas flow and it has also been tried to use materials in the off-gas channels which will prevent depositions or build-ups of dust. This has, however, not given a satisfactory solution to the depositions or build-ups of dust in the off-gas channels. In order to remove such depositions or build-ups it may be necessary to stop the furnace one to two times per shift. This gives a direct production loss and in addition, the downtime on the furnace will in itself give a poorer furnace operation.
The inventor has now found a method for preventing depositions or build-ups of dust on the walls in the off-gas channels of electrothermal smelting furnaces. Accordingly the present invention relates to a method for preventing depositions or build-ups of dust in off-gas channels for electrothermal smelting furnaces and the method is characterized in that additional gas is blown tangentially into the off-gas channels at the positions on the furnace off-gas channel which are exposed to such depositions or build-ups, whereby a surrounding gas spiral is provided between the inner wall of the off-gas channels and the dust-containing furnace off-gas.
Preferably cooled, recirculated furnace off-gas or air are used as additional gas. For completely closed furnaces where the furnace gas contains unburned explosive gases, cooled and unburned off-gas is used as additional gas. For open or semi-open furnaces air is used as additional gas.
The temperature of the additional gas which is blown into the off-gas channels is preferably kept below the sintering temperature of the dust in the dust-containing furnace off-gas.
The method of the present invention will now be further described with reference to the accompanying drawings which show by way of example an embodiment of the present invention.
FIG. 1 is a vertical view of a part of a furnace roof and a furnace off-gas channel;
FIG. 2 is a horizontal view taken along line I--I in FIG. 1; and
FIG. 3 is a vertical view of a part of a furnace roof and a furnace off-gas channel showing the cooling means.
On FIG. 1 a part of a furnace roof is indicated by reference numeral 1 having a furnace off-gas channel 2. Just above the furnace roof 1 there is provided a pipe 3 for blowing additional gas into the furnace off-gas channel 2. The pipe 3 is tangential in relation to the furnace off-gas channel 2. In the pipe 3 there is arranged a valve 4 for regulation of the flow-rate of additional gas.
In order to prevent depositions or build-ups of dust in the furnace off-gas channel 2, additional gas is blown through the pipe 3. The additional gas flows tangentially into the furnace off-gas channel and provids a surrounding gas spiral between the dust containing furnace off-gas and the inner wall of the furnace off-gas channel. This is shown by arrows on FIG. 1.
A flow pattern is then obtained which is almost non-turbulent as the furnace off-gas is put into a rotational movement. The hot, dust-containing furnace off-gas is thereby prevented from contact with the inner wall of the furnace off-gas channel and it will not be possible for the dust to deposit on the inner wall of the furnace off-gas channel. In addition the velocity of the surrounding gas spiral of the additional gas will remove any deposits or build-ups of dust on the wall. The temperature of the additional gas which is blown into the furnace off-gas channel is preperably kept below the sintering-temperature of the dust in the furnace off-gas.

Claims (5)

What is claimed:
1. A method for preventing deposits or build-ups of dust in off-gas channels for electrothermal smelting furnaces, characterized in that at the positions on the furnace off-gas channels which are exposed to depositions or build-ups of dust contained in the furnace off-gas, blowing additional gas tangentially into the channels, thereby providing a surrounding gas spiral between the dust containing furnace off-gas and the inner walls of the furnace off-gas channels, said additional gas being provided at a temperature below the sintering temperature of the dust in the dust containing furnace off-gas.
2. A method for preventing deposition or build-ups of dust in off-gas channels for electrothermal smelting furnaces, characterized in that at the positions on the furnace off-gas channels which are exposed to depositions or build-ups of dust contained in the furnace off-gas, blowing additional gas tangentially into the channels, thereby providing a surrounding gas spiral between the dust containing furnace off-gas and the inner walls of the furnace off-gas channels, said additional gas being cooled, recirculated furnace off-gas.
3. A method according to claim 1, characterized in that air is used as additional gas.
4. A method according to claim 2, characterized in that the additional gas is cooled to a temperature below the sintering temperature of the dust in the dust-containing furnace off-gas.
5. An apparatus for preventing deposits or build-up of dust in off-gas channels in electrothermal smelting furnaces comprising:
a means for blowing additional gas to said channel such that said additional gas is blown tangentially into the channel causing the additional gas to spiral between the furnace off-gas and the inner wall of the channel, said additional gas being recirculated furnace off-gas; and
means for cooling said recirculated furnace gas.
US06/710,147 1984-04-04 1985-03-11 Method for preventing dust depositions or build-ups in off-gas channels of electrothermal smelting furnaces Expired - Fee Related US4649807A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NO841319A NO154579C (en) 1984-04-04 1984-04-04 PROCEDURE FOR AA PREVENTING INVESTIGATION IN GAS OUTLETS FOR HEAT, SUSTAINABLE EXHAUSTS FROM ELECTRICAL Melting Ovens.
NO841319 1984-04-04

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US4649807A true US4649807A (en) 1987-03-17

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US06/710,147 Expired - Fee Related US4649807A (en) 1984-04-04 1985-03-11 Method for preventing dust depositions or build-ups in off-gas channels of electrothermal smelting furnaces

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US (1) US4649807A (en)
AU (1) AU553299B2 (en)
BR (1) BR8501574A (en)
CA (1) CA1243839A (en)
DE (1) DE3510723A1 (en)
IN (1) IN164498B (en)
NO (1) NO154579C (en)
YU (1) YU44018B (en)
ZA (1) ZA851849B (en)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4908058A (en) * 1986-05-09 1990-03-13 Outokumpu Oy Method and apparatus for reducing dust accretions while treating gases in a smelting furnace
US5145458A (en) * 1989-07-05 1992-09-08 Pablo Girault Method and apparatus for lifting gas streams to a great elevation in the atmosphere
US5156659A (en) * 1991-04-08 1992-10-20 Wright George T Cooler and particulate separator for an off-gas stack
US5787108A (en) * 1996-04-30 1998-07-28 Danieli & C. Officine Meccaniche Spa Exhaust device for electric arc furnaces and relative method
US6219371B1 (en) * 1999-01-20 2001-04-17 Danieli & C. Officine Meccaniche Spa System to plug the delta area of the roof of an electric arc furnace
US6535543B2 (en) * 2000-08-29 2003-03-18 Danieli & C. Officine Meccaniche S.P.A. Device to take in fumes and cool the roof of electric furnaces
US20110011211A1 (en) * 2008-03-10 2011-01-20 Outotec Oyj Metallurgical process and plant herefor

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3288130B2 (en) * 1992-11-04 2002-06-04 トピー工業株式会社 Dust accumulation prevention device for electric furnace smoke duct

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1102650B (en) * 1955-10-31 1961-03-16 Westin & Backlund Ab Pneumatic conveyor for conveying bulk goods by means of compressed air from a container into a pipeline
US3695192A (en) * 1970-10-12 1972-10-03 Joe W Von Brimer Combustion product processing device and method
US3792998A (en) * 1971-03-01 1974-02-19 Boliden Ab Method for preventing the dilution of sulphur dioxide containing waste gases obtained in copper concentrate electric smelting furnaces
DE2342844A1 (en) * 1973-08-24 1975-03-13 Schiedel Kg COLLECTION CHAMBER SECTION AND COLLECTION CHAMBER SYSTEM CONSTRUCTED FROM IT

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1102650B (en) * 1955-10-31 1961-03-16 Westin & Backlund Ab Pneumatic conveyor for conveying bulk goods by means of compressed air from a container into a pipeline
US3695192A (en) * 1970-10-12 1972-10-03 Joe W Von Brimer Combustion product processing device and method
US3792998A (en) * 1971-03-01 1974-02-19 Boliden Ab Method for preventing the dilution of sulphur dioxide containing waste gases obtained in copper concentrate electric smelting furnaces
DE2342844A1 (en) * 1973-08-24 1975-03-13 Schiedel Kg COLLECTION CHAMBER SECTION AND COLLECTION CHAMBER SYSTEM CONSTRUCTED FROM IT

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4908058A (en) * 1986-05-09 1990-03-13 Outokumpu Oy Method and apparatus for reducing dust accretions while treating gases in a smelting furnace
US5145458A (en) * 1989-07-05 1992-09-08 Pablo Girault Method and apparatus for lifting gas streams to a great elevation in the atmosphere
US5156659A (en) * 1991-04-08 1992-10-20 Wright George T Cooler and particulate separator for an off-gas stack
US5787108A (en) * 1996-04-30 1998-07-28 Danieli & C. Officine Meccaniche Spa Exhaust device for electric arc furnaces and relative method
US6219371B1 (en) * 1999-01-20 2001-04-17 Danieli & C. Officine Meccaniche Spa System to plug the delta area of the roof of an electric arc furnace
US6535543B2 (en) * 2000-08-29 2003-03-18 Danieli & C. Officine Meccaniche S.P.A. Device to take in fumes and cool the roof of electric furnaces
US20110011211A1 (en) * 2008-03-10 2011-01-20 Outotec Oyj Metallurgical process and plant herefor
US8496728B2 (en) * 2008-03-10 2013-07-30 Outotec Oyj Metallurgical process and plant therefor

Also Published As

Publication number Publication date
DE3510723A1 (en) 1985-10-24
NO841319L (en) 1985-10-07
NO154579B (en) 1986-07-21
CA1243839A (en) 1988-11-01
AU4081685A (en) 1985-10-10
DE3510723C2 (en) 1987-06-04
AU553299B2 (en) 1986-07-10
ZA851849B (en) 1986-10-29
YU44018B (en) 1990-02-28
IN164498B (en) 1989-03-25
NO154579C (en) 1986-10-29
YU55485A (en) 1988-02-29
BR8501574A (en) 1985-12-03

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Owner name: ELKEM A/S, A CORP. OF THE KINGDOM OF NORWAY

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNORS:AASEN, TORBJORN;THOGERSEN, BJARNE;REEL/FRAME:004405/0683

Effective date: 19850416

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FP Lapsed due to failure to pay maintenance fee

Effective date: 19950322

STCH Information on status: patent discontinuation

Free format text: PATENT EXPIRED DUE TO NONPAYMENT OF MAINTENANCE FEES UNDER 37 CFR 1.362